1. Field of the Invention
The present invention relates to a solid-state imaging device including plural photoelectric conversion elements which are arranged in a square lattice on a semiconductor substrate in a row direction and a column direction that is perpendicular to the row direction.
2. Description of the Related Art
In a solid-state imaging device which is useful in a digital camera, charges corresponding to image signals are detected by photoelectric conversion elements, and hence it is difficult in general to widen the dynamic range. In order to obtain an image of a wide dynamic range, therefore, it has been proposed to use a solid-state imaging device having relatively higher-sensitive photoelectric conversion elements, and relatively lower-sensitive photoelectric conversion elements (see JP-A-2001-238126).
In the imaging device disclosed in JP-A-2001-238126, rows of the high-sensitive photoelectric conversion elements, and those of the low-sensitive photoelectric conversion elements are alternately arranged. For an image based on image signals read out from the imaging device, high-sensitivity image signals due to the high-sensitive photoelectric conversion elements, and low-sensitivity image signals due to the low-sensitive photoelectric conversion elements are separately generated for respective rows. Thereafter, the image signals undergo an interpolating process to be expanded, and are then combined with each other at a predetermined mixture ratio, whereby a picked-up image signal with a wide dynamic range can be obtained.
Another solid-state imaging device is known. The solid-state imaging device is a CCD device which has photoelectric conversion elements arranged in a honeycomb pattern, and in which a hole is opened in a vertical transfer path at an imaginary pixel position, and a color filter is not disposed above the hole (see JP-A-2003-304456). Signal charges generated by light passing through the hole are those which have not been passed through a color filter. Therefore, the signal charges are used as luminance data, and image data read out from the photoelectric conversion elements are corrected in accordance with the luminance data, thereby enabling an image of high resolution and high accuracy to be produced.
However, the imaging device disclosed in JP-A-2001-238126 has a problem in that, when a picked-up image with an expanded dynamic range is to be obtained, the resolution in at least one of the longitudinal and lateral directions is lowered.
Furthermore, the sizes of the high-sensitive photoelectric conversion elements and the low-sensitive photoelectric conversion elements of the imaging device disclosed in JP-A-2001-238126 are not specifically described.